Fan



March 3, 1936.

O. L. GIBBS FAN Filed Sept. 17, `-1934 2 Sheets-Sheet 2.

ATTRNEY' Patented Mar. 3, 1936 UNITED STATES FAN Orma L. Gibbs, KansasCity, Mo., assignor of onehalf to Eugene B. Berkowitz, Kansas City, Mo.

Application September 4 Claims.

My invention relates to fans, and has for its principal object toprovide for more eicient movement of air with a minimum amount of powerwith a given size fan.

Other important features are to provide a fan structure which effectsdelivery of air at high pressures near the axis thereof, to reduce humcaused by the revolving blades, and to effect movement of the air insuch a manner to eliminate back fiow of air currents between the fanblades.

In accomplishing these and other objects o1' the invention, I haveprovided improved details of structure, the preferred forms of which areillus,- trated in the accompanying drawings, wherein:

Fig. 1 is a perspective view of an ordinary electric fan equipped with afan rotor embodying the features of the present invention.

Fig. 2 is an enlarged side elevational view of the fan rotor.

Fig. 3 is an enlarged detail view of the center of the fan rotor.particularly illustrating the hub construction. y

Fig. 4 is a cross section tnrough one of the blades on the line 4 4,Fig. 3.

Fig. 5 is a cross section through the hub of the fan on the line 5-5,Fig. 3. L

Fig. 6 is a detail perspective view of the fan rotor illustrating themovement of the air currents generated by the fan.

Fig. 7 is a perspective view of a two blade fan embodying the featuresof the invention.

Fig. 8 is a perspective view of a three blade fan.

Fig. 9 is Ia front elevational view of a six blade fan. Y

Referring more in detail to the drawings:

I designates an electric motor having its armature shaft 2 equipped witha blade fan 3 constructed in accordance with4 my invention. The fan 3 isbest illustrated in Fig. 2 and includes a hub l having blades 5, 6, 1and 9 extending radially therefrom and arranged in symmetrical pairs onthe opposite sides thereof to provide a balanced construction.

The blades 6 and 8 are preferably of shorter length than the blades 5and 1 so that the tips 9 thereof revolve in a circular plane ofdifferent diameter than the ,tips I0 of the blades 5 and -'I, therebyreducing the frequency at which the blades of one pair pass a givenpoint.

This construction considerably reduces hum generated by the rotatingblades and need not limit the capacity of the fan because the shorterblades can be constructed of greater width and can be provided with agreater angular pitch 17, 1.934, serial No. 744,333 (Cl. 23o-261) prelative to the axis of the hub than the longer blades, so that theywill move substantially the same amount of air as the longer pair ofblades. Increasing the width of the shorter blades also does not affectthe powerrequired in rotating the fan due to their shorter leverage.

The blades may be given any suitable angle of pitch depending upon thevelocity of air desired and the purpose for which the fan is to beemployed. The relative pitch and width of the blades may also be variedin wide limits. However, the relation of the side edges I I and I 2thereof bear an important relation to the hub of the fan, as now to bedescribed.

'I'he hub 4 is provided with an axial bore I3 having its end terminatingshort of the front face of the hub, as clearly shown in Fig. 5, toymount the fan on the armature shaft 2.

The fan is secured by a set screw I4 that is threaded in an opening i5extending in the hub at right angles to the axis of the bore I3, so thatthe inner end I6 of the set screw clampingly engages the armature shaftof the motor.

The hub 4 is provided with air propelling faces I1, I8, I9 and 20forming continuations of the propelling surfaces of the fan blades, butrare arranged at a. steeper pitch than the pitch of the blades to effectspiral movement of the air deiiected therefrom about the axis of thefan, as illustrated at 2 l, Fig. 6, so that air drawn in between theblades near the hub is caused to move in a spiral path in a coneformation and at high velocity toward the axis of rotation to merge withthe substantially parallel streams of air deflected from the bodyportion of the blades as indicated by the arrows 22 at a point spacedfrom the front face of the fan.

'This is a most important feature of the present invention, as thespiral movement of the air at high velocity not only adds to theeffective movement of the air, but it prevents return of the air backthrough the blades of the fan, as is the case in conventional fandesign.

Attention is also directed to the fact that tests made with my improvedfan show that air is drawn inwardly from the tips of the blade, as shownin Fig. 6, to lend to the effectiveness and efficiency of the fan.

In forming the pitch of the air propelling face of the hub, the frontside edges of the fan blades extend through a common plane and terminatein said plane at a common point on the center therefore, extremely wideadjacent the hub and have greater propelling surfaces at this point toenhance the emciency of operation. A

Also, by increasing the effective pitch at the hub, this portion of thefan is caused to perform useful work and at the same time prevents theair moved by the outer ends of the blades from moving inwardly towardthe axis of the fan,

thereby maintaining an air stream of substantially the same diameter asthat of the fan. This is an important feature, particularly Where thefan is varranged to discharge air through any opening or into an airduct.

In Fig. 7 is illustrated a modified form of fan employing two blades,wherein the edge 23 of one blade extends across the axis of rotationvinto contiguity with the corresponding edge 24 of the' other blade togive substantially the same effect as the construction shown in theforms in Figs. 2 to 6, inclusive.

InFig. 8 is shown a modified form of fan'employing three blades, thetrailing edges 26 of the fan blades terminating in the center of theaxis of rotation, as at 2l, in the same manner asshown in the four bladetype of fan.

Fig. 9 shows a still further modified form of the invention wherein sixblades are employed with alternate blades 28, 29 and 30 being of shorterlength than the other blades 3 I, 32 and 33 similar to the four bladetype, previously described. The trailing edges of the blades each extendacross the axis of rotation substantially in the same `manner as theconstruction shown inFig. 7.

While I have described the fan as being associated"with the movement ofair streams, it is obvious that the fan may be used for moving vany formof gaseous fluid without departing from the spirit of theinvention.

It is also apparent that fans embodying the same features of theinvention may be utilized -for drawing air from a source of supply byextending the opposite edges thereof` across the axis of rotation andforming the socket in the hub on the side opposite to that shown in Fig.5.

From the foregoing, it is apparent that I have provided a fanconstruction which delivers air athigh pressures at thercenter thereofand that by constructing alternate blades of different length, thefrequency at which the blades pass a outer tips of the blades to saidpoints of tenni-l nation in the axis of rotation.

2. In a fan of the character described a plurality of blades positionedat an angle to an axis l of rotation with the side edge of one bladeextending contiguously of a plane extending at right angles to the axisof rotation and termi-vv nating in said plane at a common junction withthe ,same relative side edge of an alternate blade, said blades havingpropelling surfaces extending continuously from outer tips of the bladesto said common junction.

3. A fan of the character described including a plurality of blades, anda hub supporting the blades having propelling surfaces terminating inradial edges extending contiguously of a common o plane and passingthrough a common point on the axis of the blades and in said plane, saidhub having propelling surfaces extending to said common point and havinga greater pitch angle than that of the blades.

4. In a fan of the character described, a plurality of blades arrangedsymmetrically-about an axis of rotation and 'having radial edges thereofextending contiguously of a'common plane at right angles to said axis ofrotation and lterminating in a common point at the axis of rotation .andin said pla-ne and having opposite radial edges 'converging toward saidplane, said blades having propelling surfaces extending continuouslyfrom outer tips of the blades to Said point of termination in the axisof rotation.

QRMA L. GIBBS.

